In recent years, the market of digital cameras and other imaging apparatus has been growing significantly, and users has been demanding diverse features of digital cameras and other imaging apparatus. Examples of the users' demands include high image quality, compactness, thin profile, which have been typical demands, a large magnification factor, a small f-number, and a wide imaging angle of an imaging lens, which are now greatly desired.
Among a variety of zoom lenses accommodated in an imaging apparatus, what is called a positive lead-type zoom lens, in which a lens group closest to an object has positive refracting power, is typically advantageous because a large zoom magnification factor is achieved and the optical system having a small f-number across the zoom range can be designed. A positive lead-type zoom lens is therefore employed in many cases where a high magnification factor, such as a zoom magnification factor higher than 10 times, is required.
An example of such a high-magnification, positive lead-type zoom lens is a zoom lens formed of five lens groups having positive refracting power, negative, positive, positive, and positive arranged in this order from the object side to the image side (see JP-A-2007-286446 and JP-A-2005-345968, for example).